Manufacturing method for an led

ABSTRACT

A manufacturing method for an LED includes providing a substrate having a buffer layer and a first N-type epitaxial layer, forming a blocking layer on the first N-type epitaxial layer, and etching the blocking layer to form patterned grooves penetrating the blocking layer to the first N-type epitaxial layer. A second N-type epitaxial layer is then formed on the blocking layer to contact the first N-type epitaxial layer; a light emitting layer, a P-type epitaxial layer and a conductive layer are thereafter disposed on the second N-type epitaxial layer; an N-type electrode is formed to electrically connect with the first N-type epitaxial layer, and a P-type electrode is formed on the conductive layer. The N-type electrode is disposed on the blocking layer and separated from the second 
     N-type epitaxial layer and has a portion extending into the patterned grooves to contact the first N-type epitaxial layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a divisional application of patentapplication Ser. No. 13/400,097, filed on Feb. 19, 2012, entitled “LIGHTEMITTING DIODE,” and assigned to the same assignee as this patentapplication. The parent application Ser. No. 13/400,097 is based on andclaims priority from Chinese Patent Application No. 201110181775.X,filed in the State Intellectual Property Office of China on Jun. 30,2011. The disclosures of both related applications are incorporatedherein by reference in their entireties.

BACKGROUND

1. Technical Field

The disclosure relates generally to a light emitting diode (LED), andmore particularly to an LED with an epitaxial structure having anenhanced light emitting efficiency.

2. Description of the Related Art

Light emitting diodes (LEDs) have low power consumption, highefficiency, quick reaction time, long life and an absence of toxicelements in the manufacture thereof. During operations, a current isinducted into an LED from an anode to a cathode located on the oppositeside, wherein the current may be collected in a certain region whichresults in an elevated temperature. However, a raised temperature leadsto both efficiency and the working life of the LED being reduced. Toprevent the aforesaid issues, a length of the anode or the cathode, orboth may be stretched to increase an area of the anode or the cathode orboth, whereby the conducted current can be spread over a large area toprevent the LED from having a overheating at a localized portionthereof. However, this may decrease a light emitting area of the LEDsince a portion of the epitaxial layer and the light emitting area areetched to accommodate the stretched cathode or the stretched anode.Hence, a new design of LED having a uniform current distribution and alarge light emitting area is required.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a blocking layer with patterned groovesof an LED of the disclosure.

FIG. 2 is a schematic diagram of the LED of the disclosure.

FIG. 3 is a cross section of the LED of FIG. 2.

FIG. 4 is a flow chart of the manufacturing method for the LED.

FIG. 5 is a schematic diagram showing a step of forming a vacant areawhich penetrates through an epitaxial layer of the LED according to themethod of FIG. 4.

DETAILED DESCRIPTION

Exemplary embodiments of the disclosure will be described with referenceto the accompanying drawings.

Referring to FIG. 1 and FIG. 2, the disclosure provides an LED 10, whichcomprises a substrate 12, a buffer layer 14 and an epitaxial layer 16.The substrate 12 comprises a top face 122 and a bottom face 124 oppositeto each other. The buffer layer 14 is located on the top face 122, andthe epitaxial layer 16 is disposed on the buffer layer 14. In thisembodiment, the substrate 12 is made of sapphire.

The epitaxial layer 16 comprises a first N-type epitaxial layer 162, asecond N-type epitaxial layer 164 and a blocking layer 160 sandwichedbetween the layers 162 and 164. The blocking layer 160 has patternedgrooves 1602 penetrating completely through the blocking layer 160 fromone surface to the other, whereby the first N-type epitaxial layer 162can make contact with the second N-type epitaxial layer 164 via thepatterned grooves 1602. The second N-type epitaxial layer 164 has aportion extending into the patterned grooves 1602 to engage with thefirst N-type epitaxial layer 162. Moreover, a light emitting layer 166,a P-type epitaxial layer 167 and a conductive layer 168 are disposed inthat sequence on the second N-type epitaxial layer 164.

A P-type electrode 17 and an N-type electrode 18 are formed on theepitaxial layer 16. The P-type electrode 17 is located on the conductivelayer 168, wherein the P-type electrode 17 further comprises a bondingportion 172 disposed on one end of the conductive layer 168 and anextending portion 174 with a patterned structure. The patternedstructure of the extending portion 174 on the conductive layer 168 isstaggered with the patterned grooves 1602 inside the epitaxial layer 16,as shown in FIG. 2. In this embodiment, the N-type electrode 18 and theP-type electrode 17 are generally located on the two opposite sides ofthe epitaxial layer 16 of the LED 10, wherein the

N-type electrode 18 is disposed on the blocking layer 160 and makescontact with the first N-type epitaxial layer 162 via the patternedgrooves 1602; the N-type electrode 18 is separated from the secondN-type epitaxial layer 164 and has a portion extending into thepatterned grooves 1602 to engage with the first N-type epitaxial layer162. Alternatively, the N-type electrode 18 also can be directlydisposed on the first N-type epitaxial layer 162.

The blocking layer 160 is material with a high electrical resistance andis sandwiched between the first and the second N-type epitaxial layers162, 164, and is regarded as an electron blocking layer having thepatterned grooves 1602. In one embodiment, a current I is fed into theLED 10 from the P-type electrode 17 through the conductive layer 168 andthe second N-type epitaxial layer 164 to the first N-type epitaxiallayer 162, whereby the patterned grooves 1602 of the blocking layer 160are able to uniformly allot the current I in the first N-type epitaxiallayer 162, as shown in FIG. 3. Moreover, by virtue of the extendingportion 174 of the P-type electrode 17, the current I can be moreuniformly conducted onto the conductive layer 168. Accordingly, both thelight emitting efficiency and the area from which light can be emittedof the LED 10 is enhanced due to the current I flowing through the lightemitting layer 166 more uniformly.

Referring to FIG. 4 and FIG. 5, the disclosure also provides amanufacturing method for the LED 10, which comprises the followingsteps:

In step S11, a substrate 12 having a buffer layer 14 and a first N-typeepitaxial layer 162 sequentially disposed on a top face of the substrate12 is provided. In one embodiment, the substrate 12 is made of sapphire,the buffer layer 14 is made of a III-group nitride compoundsemiconducting material, and the first N-type epitaxial layer 162 is aIII-group nitride compound semiconducting material as a contactinglayer.

In step S12, a blocking layer 160 is formed on the first N-typeepitaxial layer 162. Alternatively, the blocking layer 160 can below-doped or left undoped as a III-group nitride compound layer for theblocking of electrons.

In step S13, the blocking layer 160 is etched to form patterned grooves1602 penetrating completely through the blocking layer 160 to the firstN-type epitaxial layer 162. As shown in FIG. 1, the first N-typeepitaxial layer 162 is exposed through the blocking layer 160 via thepatterned grooves 1602.

In step S14, a second N-type epitaxial layer 164 is formed on theblocking layer 160, wherein the second N-type epitaxial layer 164 makescontact with the first N-type epitaxial layer 162 via the patternedgrooves 1602. The second N-type epitaxial layer 164 has a portionextending into the patterned grooves 1602 to engage with the firstN-type epitaxial layer 162. In this embodiment, the second N-typeepitaxial layer 164 is made of a III-group nitride compoundsemiconducting material as a contacting layer.

In step S15, a light emitting layer 166, a P-type epitaxial layer 167and a conductive layer 168 are sequentially formed on the second N-typeepitaxial layer 164. In this embodiment, the light emitting layer 166 isthe layer actually active in generating light, wherein the area of thelight emitting layer 166 equates to the light emitting area of the LED10. The P-type epitaxial layer 167 is a contacting layer of a III-groupnitride compound semiconducting material. Although conductive, theconductive layer 168 can be transparent so as not to impede the lightemitting efficiency of the LED 10.

In step S16, an N-type electrode 18 and a P-type electrode 17 areformed. The P-type electrode is formed on the conductive layer 168. Inone embodiment, as shown in FIG. 5, a depression 180 which penetratesthrough the second N-type epitaxial layer 164, the blocking layer 160,the light emitting layer 166 and the P-type epitaxial layer 167, isformed by etching. Thereafter, the N-type electrode 18 is disposed onthe first N-type epitaxial layer 162 via the patterned grooves 1602inside the depression 180. The depression 180 may occupy an area thesame as or slightly larger than that the N-type electrode 18 occupiessuch that the light emitting layer 166 of the LED 10 would not beremoved excessively. Alternatively, the N-type electrode 18 also can bedisposed on the blocking layer 160 and electrically contact with thefirst N-type epitaxial layer 162 via the patterned grooves 1602.Moreover, the P-type electrode 17 comprises a bonding portion 172 and anextending portion 174. The bonding portion 172 is disposed so as to passa working current into the LED 10 from the outside, and the extendingportion 174 is located on the conductive layer 168 for increasing thecurrent flowing area.

The embodiment provides the LED 10 containing the blocking layer 160with patterned grooves 1602, sandwiched between the first and secondN-type epitaxial layers 162 and 164. Moreover, the extending portion 174of the P-type electrode 17 is disposed on the conductive layer 168 so asto be misaligned or staggered with the patterned grooves 1602 inside theepitaxial layer 16. Therefore, the conducted current can evenly flowthrough the epitaxial layer 16 to prevent a single current hotspot andthe generation of unwanted heat. Further, since the LED 10 has a largelight emitting area, both the light emitting efficiency and theintensity of the LED 10 are enhanced.

It is to be understood, however, that even though numerouscharacteristics and advantages of the disclosure have been set forth inthe foregoing description, together with details of the structure andfunction of the disclosure, the disclosure is illustrative only, andchanges may be made in detail, especially in the matters of shape, size,and arrangement of parts within the principles of the disclosure to thefull extent indicated by the broad general meaning of the terms in whichthe appended claims are expressed.

What is claimed is:
 1. A manufacturing method for an LED (light emitting diode), comprising: providing a substrate having a buffer layer and a first N-type epitaxial layer sequentially disposed on a top face of the substrate; forming a blocking layer on the first N-type epitaxial layer; etching the blocking layer to form patterned grooves, wherein the patterned grooves penetrate the blocking layer to the first N-type epitaxial layer; forming a second N-type epitaxial layer on the blocking layer, the second N-type epitaxial layer contacting the first N-type epitaxial layer via a portion of the second N-type epitaxial layer in the patterned grooves; forming a light emitting layer, a P-type epitaxial layer and a conductive layer sequentially disposed on the second N-type epitaxial layer; and forming an N-type electrode to electrically connect with the first N-type epitaxial layer, and a P-type electrode on the conductive layer, the N-type electrode disposed on the blocking layer opposite to the P-type electrode, wherein the N-type electrode is separated from the second N-type epitaxial layer and has a portion extending into the patterned grooves to contact the first N-type epitaxial layer.
 2. The manufacturing method for an LED as claimed in claim 1, wherein the buffer layer is made of a III-group nitride compound semiconducting material, and the first N-type epitaxial layer is a III-group nitride compound semiconductor contacting layer.
 3. The manufacturing method for an LED as claimed in claim 2, wherein the blocking layer is a III-group nitride compound electron blocking layer.
 4. The manufacturing method for an LED as claimed in claim 2, wherein the second N-type epitaxial layer is a III-group nitride compound semiconducting material.
 5. The manufacturing method for an LED as claimed in claim 4, wherein the light emitting layer is a III-group nitride compound semiconductor active layer, the P-type epitaxial layer is a III-group nitride compound semiconducting material, and the conductive layer is a transparent conductive layer.
 6. The manufacturing method for an LED as claimed in claim 1, wherein the N-type electrode is located on the blocking layer and makes contact with the first N-type epitaxial layer via a portion of the N-type electrode in the patterned grooves of the blocking layer.
 7. The manufacturing method for an LED as claimed in claim 1, wherein the N-type electrode is located on the first N-type epitaxial layer.
 8. The manufacturing method for an LED as claimed in claim 1, wherein a depression penetrating through the second N-type epitaxial layer, the blocking layer, the light emitting layer and the P-type epitaxial layer is formed for accommodating the N-type electrode therein.
 9. The manufacturing method for an LED as claimed in claim 8, wherein the depression occupies an area which is substantially similar to that the N-type electrode occupies.
 10. A manufacturing method for an LED, comprising: providing a substrate having a buffer layer and a first N-type epitaxial layer sequentially disposed on a top face of the substrate; forming a blocking layer on the first N-type epitaxial layer; etching the blocking layer to form patterned grooves, wherein the patterned grooves penetrate the blocking layer to the first N-type epitaxial layer; forming a second N-type epitaxial layer on the blocking layer, the second N-type epitaxial layer contacting the first N-type epitaxial layer via a portion of the second N-type epitaxial layer in the patterned grooves; forming a light emitting layer, a P-type epitaxial layer and a conductive layer sequentially disposed on the second N-type epitaxial layer; and forming an N-type electrode to electrically connect with the first N-type epitaxial layer, and a P-type electrode on the conductive layer, wherein the N-type electrode is disposed inside the patterned grooves of the blocking layer to contact the first N-type epitaxial layer. 